Morphological separation of the Central European Trochosa females (Araneae, Lycosidae)
Martin Hepner & Norbert Milasowszky
Abstract: Adult females of the five Central European wolf spiders Trochosa hispanica Simon, 1870, T. robusta (Simon, 1876), T. ruricola (De Geer, 1778), T. spinipalpis (F. O. P.-Cambridge, 1895), and T. terricola Thorell, 1856 were morpho- logically analysed. We defined sets of continuous and binary (presence/absence) variables. Continuous data of various epigynal and carapace dimensions were subjected to Principal Components Analysis (PCA). Using the PC loadings each individual was plotted along the PC axis in order to find gaps/overlaps between the species. The binary data sets were subjected to Hierarchical Cluster Analysis (HCA) in order to find characters that clearly separate the five Trochosa species. Using PCA only individuals of T. robusta and T. ruricola and of T. robusta and T. hispanica could be separated from each other. Using HCA all five species could clearly be separated by epigynal and vulval characteristics.
key words: morphometry, spiders, taxonomy
Martin HEPNER, Department für Evolutionsbiologie, Universität Wien, Althanstraße 14, A-1090 Wien.
E-Mail: martin.hepner@univie.ac.at
Norbert MILASOWSZKY, Department für Evolutionsbiologie, Universität Wien, Althanstraße 14, A-1090 Wien.
E-Mail: norbert.milasowszky@univie.ac.at
Five species of the wolf spider genus Trochosa C. L.
Koch, 1847 occur in Central Europe: T. hispanica Simon, 1870, T. robusta (Simon, 1876), T. ruricola (De Geer, 1778), T. spinipalpis (F. O. P.-Cambridge, 1895) and T. terricola Thorell, 1856. Having ex- amined four Trochosa species (not considering T.
hispanica) ENGELHARDT (1964) found that females are very similar in size and epigynal structures and have thus to be considered sibling species. While male Trochosa species can readily be separated, the determination of the females, unfortunately, is dif- ficult to near impossible (HEIMER & NENTWIG
1991). Several attempts to distinguish preserved Trochosa material have been undertaken (e.g. DAHL
1908, CHRYSANTHUS 1955, BUCHAR 1959, EN-
GELHARDT 1964, MILASOWSZKY et al. 1998).
LOCKET & MILLIDGE (1951) separated T. robus- ta, T. ruricola, T. spinipalpis and T. terricola females on the basis of colouration and the ratio of certain measurements of the epigyne and carapace, for ex- ample the ratio between the width of the sternum measured between coxae II and the width of the triangular septum. BUCHAR (1959, see Fig. 1) sepa- rated the species according to the position and form of the “Seitenhöcker” and the form of the “mittlere
Lamelle”. ENGELHARDT (1964) concluded that body colouration, especially in females, is the only reliable character which distinguishes the species.
However, in recent determination keys genitalic characters are employed to separate the females, at least to some extent (e.g. TANAKA 1988, ROBERTS
1995). ROBERTS (1985) admitted that the “overall impression” of the epigynal structures yields more information than comparison of single parts. How- ever, MILASOWSZKY et al. (1998) demonstrated that a clear separation of T. robusta and T. ruricola is possible by morphological/morphometrical analysis of somatic and genitalic characters.
The present study expands upon the findings of MILASOWSZKY et al. (1998) by considering additional characters and taxa of Trochosa. The aim was to find reliable morphological characters, both of the epigynes and vulvae that clearly separate the females of the five Central European Trochosa species.
Material and Methods
In the present study, 207 Trochosa specimens and their epigynes were examined, of which 48 vulvae were carefully prepared (T. hispanica n = 28/4 vulvae, T. robusta n = 43/6, T. ruricola n = 48/21, T. spinipalpis n = 34/7 and T. terricola n = 54/10).
The material used was kindly provided by J. Gruber (Natural History Museum of Vienna), A. Hänggi (Natural History Museum Basel), P. Jäger, (For- schungsinstitut und Naturmuseum Senckenberg),
C. Komposch (private collection), N. Milasowszky (private collection), and P. Schwendinger (Ville de Genève, Muséum d’histoire naturelle). Reliably identified species came either from single species populations or from studies where species have already been clearly separated. The status of ten- tatively assigned and misidentified specimens was corrected after our examination.
Material examined
Forschungsinstitut und Naturmuseum Senckenberg (with SMF coll. No.): T. hispanica: F., Korsika, 9039/1, 1; 9033/1, 1; 8979/1, 1; 9077/1, 1; 8989/2, 1;
I., Sardinien, 9006/2, 2; 9011/2, 1; 9083/1, 1;
9005/1, 1; T. spinipalpis: D., Kaiserstuhl, 28628, 3;
D., Oberbayern, 33059, 7; D., Rheinland-Pfalz, Draisberghof, P. Jäger.
Komposch, C.: T. spinipalpis: A., Kärnten, near Hüttenberg, Hörfeld-Moor, 13.VI.1996, 5.
Milasowszky, N.: T. ruricola: A., Burgenland, Seewinkel, 42; T. robusta: A., Burgenland, Seewinkel, 17; T.
terricola: A., Vienna, Lobau, 18.
Natural History Museum Basel (with Coll. No.): T.
hispanica: 2373p, CH, Tessin, 29.VI.1988, 1; 2373l, CH, Tessin, 20.VII.-04.VIII.1989, 2; 2373c, CH, Tessin, V-VI.1890, Coll. E. Schenkel, 6; 2373b, CH, Tessin, 1918, Coll. E. Schenkel, 1; 2373i, CH, Tessin, 30.IV.- 14.V.1990, 2; T. robusta: 250a, CH, Umgebung Basel, 1; 250g, CH, Wallis, 28.V.-04.VI.1991, 1; 250d, CH, Umgebung Basel, 1892, Coll. E. Schenkel, 8; 250n, CH, Basel, 15.IV.-29.IV.2002, 2; T. spinipalpis:
2152m, CH, Aargau, 1972, 1; 2152l, CH, Jura, 27.VIII.1988, 1; 2152g, SK, Hohe Tatra, 31.VII.1982, 1; 2152j, CH, Waadt, 29.IV-06.V.1994, 2; 2152i, F, Elsass, 18.IV.-26.IV.1994, 1; 2152d, CH, Nidwalden,
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2152k, CH, Obwalden, 31.V.92, 1; 2152f, A, Tirol, 1; 2152e, CH, Jura, IX.1943, 1.
Natural History Museum of Vienna (with Acqu.- No.): T. hispanica: Gr., Makedonia, Chalkidiki-E, 2000.XII.30., 2; Gr., Makedonia, Krekini-Gebirge, 2000.XII.29., 1; I., Südtirol. 1990.XX.14., 2; T.
robusta: A., Burgenland, Pandorfer Platte, 1990.XXX., 3; A., Steiermark, Kalsdorf, 1986.XXII., 2;T.
ruricola: A., Vienna, 1981.XX., 3; A., Nordtirol, Innsbruck-Umgebung, Rinn, 900m, 1987.VI.1, 2;
T. spinipalpis: A., Niederösterreich, Krems, 2; T.
terricola: A., Burgenland, Pandorfer Platte, 1990.XXX., 5; A., Nordtirol, Innsbruck-Umgebung, Rinn, 900m, 1987.VI.1, 14; A., Wien/Niederösterreich, Wienerwald, 5 (priv. coll. Gruber).
Ville de Genève, Muséum d’histoire naturelle: Material:
Araneae: Lycosidae, F.36, S.f.2: T. hispanica: CH, Ticino, Melera, Vorwand, 11.IX-24.IX.1988, det. A. Hänggi, 1;
T. spinipalpis, Russia, Bashkiria, Ufa, park, VII. 1979, leg.
Bliss, ex coll. S. Heimer, 2; D, Dresden, ex. coll. S.
Heimer, 2; CH, Altenburg, 2.
Morphological/morphometrical analysis The entire material was preserved in ~70% alcohol.
Remaining tissues from the prepared vulvae were removed with pins and by boiling in 4% KOH.
A total of 28 characters were examined from the material including ten continuous (interval-sca- led), two categorical (ordinal-scaled) and 16 binary (presence/absence) characters (Tab. 1 & 2). The continuous characters (Fig. 1, A-H, Tab. 1) compri- se two variables of the carapace and eight of the epi- gyne (n = 207). The two categorical characters are the inner and outer row of the cheliceral margin.
Fig. 1: Schematic drawing of a Trochosa epigyne showing the continuous (A-H) and binary (presence/absence) (I-M) variab- les used in this study. Distances show length of continuous variables, arrows point to binary characters. A = height of epigynal plate; B = width of epigynal plate; C = maximum width of triangular septum; D = outer distance between septal margins before expanding posteriorly into triangular septum;
E = maximum distance between arches of anterior transverse pockets (= posterior part of helmet-shaped broadenings of vulva); F = distance between distal part of transverse pockets and distal transverse edge of epigynal plate; G = medial distance between transverse pockets; H = distance between inner edges of distal part of transverse pockets; I = inner margin of helmet-shaped broadenings of vulva; J = course of inner margins of helmet-shaped broadenings of vulva; K = hel- met-shaped broadenings of vulva; L = shape of dark markings anterior to transverse pockets; M = appendices of basal part of copulatory ducts.
Continuous characters cl length of carapace
cw width of carapace A height of epigynal plate B width of epigynal plate
C maximum width of triangular septum D outer distance between the septal margins
before expanding posteriad into the triangular septum
E
maximum distance between the arches of the anterior transverse pockets (= posterior part of the helmet-shaped broadenings of the vulva)
F distance between the distal part of the transverse pockets and the distal transverse edge of the epigynal plate
G medial distance between the transverse pockets
H distance between the inner edges of the distal part of the transverse pockets Among the binary characters eleven were obtained
from the epigyne (Fig. 1, Tab. 2) (n = 205) and five from the vulva (Fig. 2, Tab. 2) (n = 48).
Statistical analysis
The continuous characters (Fig. 1 & Tab. 1, A-H) were subjected to Principal Components Analysis (PCA) using the correlation matrix and varimax rotation solution. Only principal components that accounted for variances greater than one (Kaiser criterion) were used to represent the data.
The binary characters of the epigyne and vulva (Fig. 1 & 2, Tab. 2) were separately subjected to Hierarchical Cluster Analysis (HCA) using the average linkage between groups (UPGMA) as a cluster method. Two different measurements were used: (i) the squared Euclidian distance for the set of continuous variables and (ii) the Lance and Williams index for the binary data set.
All statistical analyses were preformed using SPSS for Windows, Version 11.5 (NORUISIS
1990).
Results
Principal Component Analysis
Principal Component Analysis (PCA) of the 10 continuous characters (Fig. 1, Tab. 1) yielded two factors, PC1 and PC2. The first principal compo- nent, PC1, accounted for 55.7% of the total varia- tion. Characters highly correlated with this axis are:
(1) cl, the length of the carapace; (2) cw, the width of the carapace; (3) A, height of epigynal plate;
(4) B, width of epigynal plate; (5) C, maximum
width of triangular septum; and (6) E, maximum distance between the arches of the anterior trans- verse pockets.
The second principal component, PC2, ac- counted for 14.7% of the variation. Characters highly correlated with this axis are: (1) F, distance between the distal part of the transverse pockets and the distal transverse edge of the epigynal plate; (2) H, distance between the inner edges of the distal part of the transverse pockets; and (3) G, medial distance between the transverse pockets. Both prin- cipal components together accounted for 70.3% of the total variation in the morphometrical data set (Fig. 1, Tab. 1). A clear separation of all five spe- cies was not possible along these axes. However, T. robusta and T. ruricola could be separated. Also T. robusta and T. hispanica show a clear separation along PC2. Only a small overlap is found between T. terricola and T. robusta. All other species exhibit large overlaps (Fig. 3).
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Tab. 1: Continuous characters measured on the carapace and epigynes of T. hispanica (n = 28), T. robusta (n = 43), T.
ruricola (n = 48), T. spinipalpis (n = 34) and T. terricola (n = 54).
Fig. 2: Schematic drawing of a vulva showing the binary (presence/absence) (M-P) variables used in this study.
M = appendices of basal part of copulatory ducts; N = appendix of spermatheca; O = lateral enlargement of copulatory duct; P = copulatory duct.
Hierarchical Cluster Analysis
The ordination of binary variables on the epigyne (Fig. 1 & 2, Tab. 2) showed that a reliable separa- tion of all five Trochosa species is possible (Fig. 4 a).
In most cases the species can be separated by the epigynal characters (Fig. 1, Tab. 2). If determina- tion using these characters is not possible, then the characters of the vulvae (Fig. 2, Tab. 2) allow clear separation between the species. Unfortunately, the vulva data of T. hispanica was excluded from the analysis due to high intraspecific variation. The examination of the remaining data set showed a clear separation between the species (Fig. 4 b).
T. ruricola can be separated from all other Tro- chosa species by the convex formed inner margins of the helmet-shaped broadenings of the vulva (I), the short appendices on the spermathecae (N) and the short and massive copulatory ducts with a clearly visible constriction (P) (Fig. 5, I a & b).
T. hispanica has, in contrast to all other Central European Trochosa species, uniquely formed, dark markings anterior to the transverse pockets (L) and very bright helmet-shaped broadenings of the vulva (K) (Fig. 5, II a).
T. terricola has large appendices on the basal part of the copulatory ducts (M) which shine through the epigyne plate and are even clearly visible in the unprepared epigyne (Fig. 5, III a & b).
The remaining two species can be separated by the course of the inner margins of the helmet- shaped broadenings of the vulva ( J) which are parallel in T. robusta (Fig. 5, IV a & b) and diverge forwards in T. spinipalpis in most cases. However, in 3% of the T. spinipalpis specimens the inner margins are parallel as in T. robusta. In comparison to T.
robusta, T. spinipalpis has long appendices on the spermathecae (N) (Fig. 5, V b) while the appendices are short in T. robusta (Fig. 5, IV b).
Dentition
The dentition characters of the inner and outer row of the cheliceral margins overlap among the species (Tab. 3). Intraspecific differences are also apparent in the dentition. Furthermore, in all species, except T. hispanica, the dentition of the cheliceral margins varies even within single specimen (Tab. 3).
Binary characters
Epigyne
I inner margin of the helmet-shaped broadenings of the vulva
(1) straight (2) bowed/convex J course of the inner margins of the helmet-
shaped broadenings of the vulva
(1) margins parallel (2) margins divergent K helmet-shaped broadenings of the vulva (1) clearly visible
(2) distally pointed L shape and length of the dark markings anterior
to the transverse pockets (= posterior part of the helmet-shaped broadenings of the vulva
(1) margins nearly parallel and extending to the apical edge of the basal part of the copulatory ducts (without appendices) (see Fig. 5) (2) margins bowed and shorter M appendices of the basal part of the copulatory
ducts
(1) clearly visible through the epigynal plate
(2) large, nearly extending to area where the septum turns beneath the transverse pockets
(3) small
Vulva
N appendices of the spermathecae (1) large (2) none or small O lateral enlargement of the copulatory duct (1) large/clearly visible
P copulatory duct (1) short/massive with constriction
(2) more or less long/thin without constriction
Tab. 2: Binary characters measured on the epigynes (I-M) and vulvae (N-P) of T. hispanica (n = 4), T. robusta (n = 6), T. ruricola (n = 21), T. spinipalpis (n = 7), and T. terricola (n = 10).
Discussion
In this study we analysed 207 female Trochosa specimens originating from Austria, Germany, Greece, Italy, Russia and Switzerland in order to guarantee general statements about reliable sepa- rating characters within the five Central European Trochosa species.
Several authors have proposed a number of poten- tial separating characters (concerning dentition, body colouration, habitat and presents of males) to which we will refer in the following discussion.
Our results about the dentition of the cheliceral margins agree with the findings of BUCHAR (1959,
species dentition of cheliceral margins
3-3/3-3 2-3/2-3 2-2/2-2 3-3/2-3 2-2/2-3 1-2/2-3 1-3/2-3
Trochosa hispanica 100
Trochosa spinipalpis 55,88 35,29 8,82
Trochosa ruricola 79,17 4,17 10,42 4,17
Trochosa robusta 97,67 2,33
Trochosa terricola 90,57 3,77 1,89 3,77
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Tab. 3: Dentition characters of T. hispanica (n = 28), T. robusta (n = 43), T. ruricola (n = 48), T. spinipalpis (n = 34) and T. terricola (n = 53) in percent. Notation: left inner row – left outer row / right inner row – right outer row; inner row = posterior cheliceral tooth; outer row = anterior cheliceral tooth (ROBERTS 1995, p. 15).
Fig. 3: Scatter plot of scores resulting from Principal Components Analysis with continuous characters representing Trochosa females on the two components axes (PC 1-2). te = Trochosa terricola; sp = T. spinipalpis; ru = T.
ruricola; ro = T. robusta; hi = T. hispanica.
Fig. 4: Dendrogram illustrating the taxonomical separation of Trochosa females according to Hierarchical Cluster Analysis on a, epigynal and b, vulval characters.
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Tab. 1), ENGELHARDT (1964, Tab. 4) and MILA-
SOWSZKY et al. (1998) that this character cannot be used for separation of Trochosa females due to high variability. Differences in the dentition occur not only within species/populations but also within the left and right chelicera of single specimens.
ENGELHARDT (1964) preferred body coloura- tion as a separation criterion: “Lediglich die Fär- bung ist ein sicheres beiden Geschlechtern eigenes Unterscheidungsmerkmal der vier Arten”. However, he also mentioned in this study that: ”…die Kör- perfarbe, ein Kennzeichen, das bei konserviertem Material nicht mehr voll brauchbar ist.” We entirely concur with Engelhardt that body colouration is useful for determining live material of Trochosa and that it is problematic for stored material. Coloura- tion changes in relation to storage time and storage medium have been documented by MILASOWSZKY
et al. (1999) and LOCKET & MILLIDGE (1951).
Therefore, colouration could not be used as a sepa- rating character in our study, since we exclusively examined museum specimens stored in alcohol.
DAHL & DAHL (1927) favoured habitat and natural history characters:”…wir sind bei der Unterscheidung der Arten hauptsächlich auf die Unterschiede im Vorkommen und in der Lebens- weise angewiesen.” However, separation according to life pattern is suitable when live spiders can be observed in the field, but not for museum material.
The usefulness of such traits for determination is thus greatly diminished.
A common method of determining female spiders is to assign them to co-occurring males of the same genus. This method is very problematic because of the co-occurrence of other Trochosa species.
HÄNGGI et al. (1995) showed, for example, that T. terricola, the most common of the five Trochosa species, occurred in 82% of the sites of T. robusta, in 66% of the areas of T. spinipalpis and in 45% of the areas of T. ruricola. T. ruricola also occurs in 42% of the areas of T. spinipalpis. In other words, ecological preferences and the occurrence of specific males may serve as indications, but cannot ensure an accurate determination of "unknown" females.
The result of the PCA performed in this study confirms the results of MILASOWSZKY et al. (1998) that the females of T. robusta and T. ruricola can be separated by morphometrical characters. How- ever, the separation of these two species was, in this study, not as clear as it was in MILASOWSZKY et al. (1998). We obtained a clear separation only for T. robusta and T. hispanica in the actually studied material along PC2. All other species showed large overlaps and could therefore not be separated by the morphometrical features we used in our study.
The present study, however, shows that a clear determination of the investigated Trochosa material is possible by examination of nominal morphologi- cal characters. These characters are taken from the epigyne and the vulva. In summary, we identified at least seven characters that allow a clear separation of the five Trochosa species. These characters are 1, the form of the inner margin of the helmet-shaped
Fig. 5: Photographs of a, epigynes and b, vulvae of I, T. ruricola, II, T. hispanica, III, T. terricola, IV, T. robusta and V, T. spinipalpis. I = inner margin of helmet-shaped broadenings of vulva, J = course of the inner margin of the helmet-shaped broadenings of the vulva, N = appendix of the spermathecae, P copulatory duct, M = appendix of the basal part of the copulatory ducts, L = shape of the dark marks anterior to the transverse pockets and K = helmet-shaped broadenings of the vulva.
broadenings of the vulva; 2, the course of the inner margins of the helmet-shaped broadenings of the vulva; 3, the size of the appendix of the sperma- thecae; 4, the shape of the copulatory duct; 5, the occurrence and size of the appendix of the basal part of the copulatory ducts; 6, the shape of the dark marks anterior to the transverse pockets; and 7, the appearance of the helmet-shaped broadenings of the vulva. Nevertheless, in most cases a combination of epigynal and vulval characters is the best way to guarantee a clear identification of females of the five Central European Trochosa species.
Identification key
1 Helmet-shaped broadenings clearly visible and their inner margins convex (Fig. 5, I a); copulatory ducts short, massive with a constriction (Fig. 5, I b) . . . . ruricola – Helmet-shaped broadenings nearly invisible (Fig. 5, II a) or the inner margins of the helmet-shaped broadenings straight (Fig. 5, f. e. V a) . . . 2 2 Helmet-shaped broadenings nearly invisible; dark marks anterior to the transverse pockets long and nearly parallel (Fig. 5, II a). . . hispanica – Not like this . . . 3 3 Appendices of the basal part of the copulatory duct large and clearly seen through the epigyne (Fig. 5, III a
& b). . . terricola – Not like this . . . 4 4 inner margins of the helmet-shaped broadenings of the vulva parallel; copulatory ducts with only small appendices (Fig. 5, IV a & b) . . . robusta – inner margins of the helmet-shaped broadenings of the vulva (in most cases) divergent; copulatory ducts with large appendices (Fig. 5, V a & b) . . . spinipalpis
Acknowledgments
The authors thank our project supervisor Prof. Dr. H.
F. Paulus, University of Vienna, for his support. Further thanks are due to J. Altmann (Forschungsinstitut und Naturmuseum Senckenberg), J. Gruber (Natural History Museum of Vienna), A. Hänggi (Natural History Museum Basel), P. Jäger (Forschungsinstitut und Naturmuseum Senckenberg), P. Schwendinger (Ville de Genève, Muséum d’histoire naturelle) and C.
Komposch for kindly providing preserved specimens.
Thanks are also due to the University of Vienna for the award of the "Forschungsstipendium 2005" that made it possible for us to accomplish the project. We also appreciate J. Plant for linguistic help and the referees D. Cordes and T. Kronestedt for valuable comments on the manuscript.
References
BUCHAR J. (1959): Beitrag zur Bestimmung der mitteleu- ropäischen Arten der Gattung Trochosa (C. L. Koch).
– Acta Univ. Carol. Biol. 1959: 159-164
CHRYSANTHUS F. (1955): Notes on spiders II. About some females of the genus Trochosa (C. L. Koch 1846).
– Ent. Bericht. 15: 518-520
DAHL F. (1908): Die Lycosidae oder Wolfspinnen Deutschlands und ihre Stellung im Haushalt der Natur. Nach statistischen Untersuchungen darge- stellt. – Nov. Act. Acad. Caes. Leopold-Carol. 88:
175-678, Taf. 17
DAHL F. & M. DAHL (1927): Spinnentiere oder Arach- noidea. Lycosidae s. lat. (Wolfspinnen im weiteren Sinne). – Tierwelt Deutschlands 5: 1-80
ENGELHARDT W. (1964): Die Mitteleuropäischen Ar- ten der Gattung Trochosa C. L. Koch, 1848 (Araneae, Lycosidae). Morphologie, Chemotaxonomie, Biologie, Autökologie. – Z. Morph. Ökol. Tiere 54: 219-392 HÄNGGI A., E. STÖCKLI& W. NENTWIG (1995):
Lebensräume Mitteleuropäischer Spinnen. – Misc.
Faun. Helv. 4: 1-459
HEIMER S. & W. NENTWIG (1991): Spinnen Mittel- europas: Ein Bestimmungsbuch. Verlag Paul Parey, Berlin & Hamburg. 542 pp.
LOCKET G.H. & A.F. MILLIDGE (1951): British spiders, I. Ray Society, London. 310 pp.
MILASOWSZKY N., J. BUCHAR & K.P. ZULKA (1999):
Morphological variation in Pardosa maisa Hippa &
Mannila 1982 (Araneae, Lycosidae). – Senck. biol.
79: 11-18
MILASOWSZKY N., M.E. HERBERSTEIN & K.P. ZULKA
(1998): Morphological separation of Trochosa robusta (Simon, 1876) and Trochosa ruricola (De Geer, 1778) females (Araneae: Lycosidae). In: Proceedings of the 17th European Colloquium of Arachnology, Edin- burgh 1997. pp. 91-96
NORUISIS M.J. (1990): SPSS advanced statistics student guide. SPSS Inc. Chicago. 506 S.
ROBERTS M.J. (1985): The spiders of Great Britain and Ireland, 1. Harley Books, Colchester/Essex. 229 pp.
ROBERTS M.J. (1995): Collins field guide. Spiders of Britain & Northern Europe. HarperCollins, London.
383 pp.
TANAKA H. (1988): Lycosid spiders of Japan II. The genus Trochosa C. L. Koch. – Acta arachnol. Tokyo 36: 93-111
